I think the third time is the charm for Texas and the Pac 12. They will both find a way to get it done. The Pac will make concessions that it would not make before, and after losing ground to the Texas A&M after it joined the SEC, Texas will want to join the one conference that could overtake the SEC in prestige and talent (as long as UT and OU are in it).
It wouldn't surprise me if it happened much earlier than the contract expiration.